Material and process for making multicolor subtractive photographic prints



J. G. CAPSTAFF MATERIAL AND PROCESS FOR MAKING MULTICOLOR SUBTRAGTIVEPHOTOGRAPHIC PRINTS Filed Nov. 12. 1951 Aug. 7, 1934.

Szppori slygpofi Sensitive emulsion Conwa a reslnu'nirg dye Qwuentoo:

' aux/mar Patented Aug. 7, 1934 UNITED STATES MATERIAL AND PROCESS FORMAKING MULTICOLOR SUBTRACTIVE PHOTO- GRAPHIC PRINTS John G. Capstaif,Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., acorporation of New York Application November 12, 1931, Serial No.5'l4,534

10 Claims.

This invention relates to color photography and more particularly to amaterial and process for making multi-color subtractive photographicprints in which several component color images are formed on each sideof a double coated film. The invention describes a new type of film tobe used for such a process.

In processes previously described for producing a plurality of colorimages on a double coated film, such as for example a process involvingone component image on one side and two on the other, it has beennecessary to carry out several printing and drying operations. It is oneof the objects of my invention to reduce the number of separate printingand intermediate drying operations required in such a process.

' The new film which I use consists of a transparent support coated oneach side with a photographic emulsion of the positive type, one or bothof the emulsion'layers containing a water soluble dye to limit thepenetration of the actinic' light rays, and a layer of water-proofvarnish being coated over the emulsion on one side of the. film. Thiswater-proof varnish is re.- movable by solution in organic or othersolvents or by other suitable means.

Reference is made to the accompanying drawing in which i Figure .1 is across section on an enlarged scale of a film made according to myinvention.

Figure 2 is a similar cross section of a preferred form of film which Iuse in my invention.

A transparent support 1 such as a film of cellulose nitrate orcelluloseacetate for example, is coated on either side with positivesensitive emulsion 2 and 3 (Figure 1) or 2' and 3 (Figure 2). Overeither of these emulsions isplaced a very thin coating of a water-proofvarnish 4.

In the preferred form of this film (Figure 2), one of the emulsionlayers contains a light restraining dye, such' a dyed emulsion coatingbeing shown as 2' in Figure 2.

Dyes which are suitable as light restraining dyes to be placed in theemulsion as described are tartrazine, acid yellow, filter K, andnaphthol yellow.

For the varnish layer 4 any suitable waterproof varnish which is solublein a solvent which will not distort the upport may be used. An

example of such a varnish is-the following:

Cellulosebenzyl ether 150 g. Benzene 1550 cc. Toluene 100- cc. Xylene400 cc.

This coating may be easily removed with benzene. One of the mostadvantageous uses of such afilmisinthemakingofathreecolor subtractiveprint, by which I will illustrate its use. The film described is exposedfrom the one side through one of the three color component negatives,say the red negative, and from the;

other side, in register, through another of the component negatives, saythe green. These exposures may be made simultaneously or in succession,and by contact or projection.

Let it be assumed that the exposure from the unvamished side of the filmwas made through the red filter component negative. The film is thendeveloped by immersion in a developer that produces, in addition to thesilver image, anaccompanying image of an insoluble blue-green dye.

Typical developers are the following:

The film is now washed and passed through a soc.c. .5 g. 0 g.

lution that converts the silver image to one of a silver salt, such as asolution 0f potassium ferricyanide and potassium bromide. The silversalts are 'now removed with a solution of plain sodium thiosulphate, andthe film'is thoroughly washed.

in water. It is understood that the above solutions and wash waters actonly upon the'unvarnished side of the film.

In producing this colored image, as well as the. following ones, it isnot essential that a color forming developer be used. The image can beproduced by any recognized method, as for example, by dye toning.Numerous examples of typical dye-toning processes are to be found in"The Tinting and Toning of Eastman Positive Motion Picture Film, fourthedition, published by Eastman Kodak Co., Rochester, N. Y., 1924. It musthowever, not be' affected by any of the subsequent operations.

I prefer to varnish this first image, as this side, the originallyvarnished side. At this stage the. steps, then are (1) The film ispassed through (immersed in) asuitable organic solphenylene diamine.

- Ammonium bromide -1 vent, such as benzine,-which removes the varnishlayer from theundeveloped side of the film. (2) The developed side(first image) is then varnished.

Let it be assumed that the undeveloped side of the film has beenexposed, in the above described printing -'operation, through the greenfilter component negative. The film is now developed by immersing in adeveloper that produces, in addition to the silver image, an accom-Water to 100 c. c

The film is now washed and passed through a solution that converts thedeveloped silver to a salt of silver not susceptible to developmentwithout further exposure to light and destroys any remaining latentimage. Such a solution is the following.

24 grams Iodine 0.5 gram Water to 500 c. c.

This. bath is used so that any remaining undeveloped latent image willnot develop in the yellow developer without further exposure to light.Otherfwisesome of the image which should have'been magenta will becomeyellow. The film is now washed and passed through a sensitizing bath,such as for example a solution of sodium sulphite.

At this stage, before printing the third image, it is desirable tore-introduce a yellow light restraining dye similar to that originallypresent in the film. This is necessary to produce the same gamma in thethird image as in' the other two,

and to restrict the depth of this third image to the lower part of thelayer in which it is printed from the opposite side. The yellow dye maybe conveniently introduced by dissolving about /2% of the dye(tartrazine, acid yellow or others) in the /2% sodium sulphitesensitizing solution.

After drying, the film is again exposed, through the first developed andfixed side (the originally unvarnished side), to the third colorcomponent negative, say the blue, in registry with the first two images..The film is now developed by immersing in a developer that produces, inaddition to the silver image, an accompanying image of a yellow colorsuch, for instance, as a mixture'of alpha-chlorethylaceto acetate withdiethyl para- The film is now washed and passed through a solution thatconverts the silver image to one of a silver salt, such as a solution ofpotassium ferricyanide and potassium bro-' mide. All the remainingsilver salts arenow removed with a solution of plain sodiumthiosulphate, and the film is thoroughly washed and dried. It now bearsthe completed three color.

' subtractive print.

The order of introducing the three color images is not essential,although it is preferable that the first introduced image be eitherblue-green a transparent, waterproof coating, submitting the necessityfor color sensitizing the film or for printing through filters. Otherdevelopers such as those disclosed in the patents to Fischer 1,055,155,March 4, 1913 and 1,102,028, June 30, 1914, and disclosed in "History ofThree-Color Photography? by E. J. Wall, published 1925, pages 404 -etseq., may be used.

All of the developers and solutions which I use are well known in theart and have been previously described. They form no partof the presentinvention.

By the process described only two printing operations and oneintermediate drying of the film are required to introduce three images.

The special film described may also be'used to advantage in theproduction of two color subtractive prints in which both images areprinted at the beginning and the iodine bleach and sulphite sensitizingbaths or their equivalents, as well as the third exposure anddevelopment, are

' omitted. It will be apparent that a number of other variations arepossible at the difierent stages.

I consider as included-in my invention all varitions and equivalentscoming within the scope of the appended claims. 1

What I claim is:

1. A film for a color photographic process in which color componentimages are formed on each side of a film, comprising a transparentsupport, at least one sensitive emulsion layer on each side of saidsupport and a thin, easily removable, waterproof coating over one ofsaid sensitive layers.

2.A film for a color photographic process in which color componentimages are formed on each side of a film, comprising a transparentsupport, a sensitive emulsion layer oneach side of said support, a watersoluble dye in one of said emulsion layers to limit the penetration ofeifective light rays, and a thin coating of a waterproof varnish whichis readily removable in suitable solvents over one of said sensitiveemulsion layers.

3. ,m a color photographic process, the steps that comprise printingfrom color separation negatives upon opposite sides of a film having asensitive emulsion layer on each surface, one of which layers iscovered-by a waterproof protectivelayer, thereby forming in registrylatent images in each sensitive layer, transforming one latent. imageinto a color image without aflecting the latent image in the layer underthe protective coating and then removing the protective coating andtransforming the other latent image into a color image. 4. A colorphotographic process comprising forming different color component latentimages in two sensitive layers on opposite sides of the same film, oneof said layers being covered by the film to a color forming developerwhereby a colored image is formed in the uncovered layer, removing saidcoating and submitting the film to a diiferent color forming developerwhereby an image of diiferentv color from the first is formed in thepreviously protected layer.

5. A color photographic process which comprises the making of threecolor separation 'negatives through different color filters, printingfrom two of said negatives in register upon opposite sides of a filmhaving a sensitive layer on each side and having a waterproof layer overone sensitive layer, thereby forming latent images in each layer,transforming the latent image in the uncovered sensitive layer into acolor image, removing the protective coating, transforming the otherlatent image into a color image, and then forming in one, of said layersa color image from the third separation negative.

6. Acolor photographic process which comprises the making of three colorseparation negatives through different color filters, printing from twoof said negatives in register upon opposite sides of a film having asensitive layer on each side and having a waterproof layer over onesensitive layer, thereby forming latent images in each layer,transforming the latent image in the uncovered sensitive layer into acolor image, removing the protective coating, transforming the otherlatent image into a color image, resensitizing one of said layers andprinting therein a latent image from the third negative and transformingthis last named image into a third color image, the three color im--ages being of different colors and each complementary to the color ofthe filter through which the corresponding negative was taken.

'7. A color photographic process which comprises making three colorseparation negatives through different colorfilters, printing 'two ofsaid separation negatives in register upon opposite sides of a positivefilm having an emulsion layer on each surface and which contains a watersoluble light restraining dye in one emulsion layer and has a thinwaterproof varnish layer over one of the emulsion layers, developing thefilm in a color-forming developer, converting the silver imageassociated with the'color image into a silver salt, removing the varnishlayer from the undeveloped side of the film, developing the film in -asecond color forming developer, submitting the film to the action of anoxidizing solution that converts the developed silver to a salt ofsilver which is not susceptible to development without further exposureto light and destroys any remaining latent image, resensitizing one ofthe emulsion layers, printing in register in the resensitized layer thethird color separation negative, developing the third image so producedin a third color-forming developer, submitting the film to the action ofa solution that converts thesilver image to a silver salt, and removingall the remaining silver salts.

8. A color photographic process which comprises making three colorseparation negatives through different color filters, printing two ofsaid separation negatives in register upon opposite sides of a positivefilm having an emulsion layer on each surface and which contains a watersoluble light restraining dye in one emulsion layer and has a thinwaterproofvarnish layer over one of the emulsion layers, developing thefilm in a color-forming developer that gives a product complementary. incolor to that of the filter used in taking the color separation negativewhich is printed on the unvarnished side of the said positive film,converting the silver image associated with the color image into asilver salt. removing the converted silver salts, removing the varnishlayer from the undeveloped side of the film, developing the film in asecond color forming developer that produces a product complementary incolor to that of the filter used in taking the color separation negativewhich is printed on the varnished side of the said positive film,submitting the film to the action of an oxidizing solution that convertsthe developed silver to a salt of silver whichis not susceptible todevelopment without further exposure to light and destroys any remaininglatent image, resensitizing one of the emulsion layers, printing inregister in the resensitized layer the third color separation negative,developing the third image so produced in a third color-formingdeveloper that gives a product complementary in color to-that of thefilter used in taking said third colorseparation negative, submittingthe film to the action of asolution that converts the silver image to asilver with the color image into a silver salt, removing the varnishlayer from the undeveloped side of the film, varnishing the developedside, developing the film in a second color forming developer,

submitting the film to the action of an oxidizing solution that convertsthe developed silver to a salt of silver which is not susceptible todevelopment without further exposure to light and destroys any remaininglatent image, resensitizing the film, printing in register on theoriginally unvarnished side the third color separation negative,developing the third image so produced in a thirdcolor-forming-developer, converting the silver image to a silver saltand removing all the remaining silver salts. h

10. A color photographic process which comprises making three colorseparation negatives through diiferent color filters, printing two ofsaid separation negatives in register upon opposite sides of adouble-coated positive film which contains a water soluble lightrestraining dye in one emulsion layer and has a thin waterproof solublevarnish layer over-one of the emulsion layers, developing the film in acolor-forming .i

developer that gives a product complementary in color'to that of thefilter used in taking the color separation negative which is printed onQ the unvamished side of the said positive film, converting the silverimage associated with the color image into a silver salt, removing theconverted silver salt, removing the varnish layer from the undevelopedside of the film, varnishing the developed side, developing the film ina second color forming developer that produces a sure to light anddestroys any remaining latentimage, resensitizing the film and bathingit in a yellow light-restraining dye, printing in register on theoriginally unvarnished side the third color separation negative,developing the third image so produced in a third color-formingdeveloper that gives a product complementary in color to that of thefilter used in taking said third color separation negative, convertingthe silver image to a silver salt and removing all the remaining silversalts.

JOHN G. CAPSTAFF.

